The present invention relates to an optical test chart for testing binocular reading ability. Polarization filters having directions of vibration crossed with respect to each other are arranged in front of the eyes of the test subject, and through these, the subject views the test chart containing polarized indicia.
Optical test charts are known which contain figures composed of two parts, the different parts of the figures being formed with polarizing action with directions of polarization extending crosswise with respect to each other. The test subject therefore sees only a part of the figures with each eye. With normal binocular reading ability these two optically separate visual impressions appear to the test subject as a single figure.
Optical test charts are also known which contain two or more letters in each of two horizontal lines. The letters of each line have polarizing action with directions of polarization extending crosswise with respect to each other and are arranged in such a manner that letters which stand next to each other horizontally or one above the other vertically have directions of polarization which are crossed relative to each other. The test subject therefore sees four or five letters in the case of normal vision.
All of these optical test charts require a certain concentration on the part of the test subject since he must describe the picture seen by him. The examiner can draw his conclusions only from the description given to him by the person being tested.